JP3156554B2 - Fuel injection valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve, in particular, a metering member having an injection hole at the tip of a valve body, and injecting fuel from the injection hole to measure the fuel and to determine the injection direction. The invention relates to a type of fuel injector for making decisions.

[0002]

2. Description of the Related Art A measuring member having a plurality of injection holes is provided at an outlet of a fuel discharge passage formed at a distal end portion of a valve body.
A fuel injection valve of a type that measures fuel and determines the injection direction by injecting fuel from the injection hole is known (Japanese Utility Model Laid-Open No. 3-92564, Japanese Utility Model Laid-Open No. 3-10416).
No. 6).

[0003]

In the fuel injection valve disclosed in the above publication, the fuel that has passed through the seal portion of the needle valve that opens and closes the fuel flow path is generally led to the injection hole without any change. Although the kinetic energy of the fuel cell is suppressed from being attenuated, the fuel enters the combustion chamber in the form of a liquid column or a liquid film, and the fuel is not sufficiently atomized. In view of the above, the applicant of the present application has previously proposed in Japanese Patent Application No. 7-078920 a method in which a protrusion facing the fuel discharge passage is provided at the tip of the needle valve. So that the fuel that has passed through the seal portion flows first toward the measuring member, and after hitting the measuring member, is directed toward the center along the measuring member. A fuel injection valve has been proposed which is configured to facilitate separation and promote self-excited oscillation of a fuel column and a liquid film to promote atomization of fuel. However, in the case of the configuration as in the above-mentioned application, since the fuel that has passed through the seal portion has a strong flow in the vertical direction and is rapidly converted into a flow in the horizontal direction, the kinetic energy is greatly attenuated, and the fuel is injected. There was a problem that the fuel was not sufficiently separated at the hole entrance, and the kinetic energy of the fuel could not be effectively used for atomization. The present invention has been made in view of the above problems, and in a fuel injection valve in which a measuring member having an injection hole is disposed at a distal end portion of a valve body, a kinetic energy of fuel is suppressed from being attenuated, and a fuel flow at an injection hole inlet is separated. An object of the present invention is to improve the atomization of fuel by facilitating atomization.

[0004]

According to the first aspect of the present invention, there is provided a valve body, a needle valve which is received inside the valve body and opens and closes a fuel flow path in a seal portion, In a fuel injection valve provided with a plurality of injection holes and having a measuring member for measuring fuel and determining an injection direction, an inner wall surface downstream of a seal portion of the valve body is provided on an upstream surface of the measuring member. When the needle valve is opened, the seal portion of the needle valve and the bottom surface on the most downstream side cooperate with the inner wall surface downstream of the seal portion of the valve body to distribute fuel to the metering member. Are connected via a conical surface forming a fuel flow path inclined inward and downstream to be introduced into the provided injection hole, and when the needle valve is opened, the conical surface faces the upstream surface of the measuring member. When extended, the intersection line formed to intersect with the upstream surface of the measuring member is formed so as to be outside the circumscribed circle of the upstream opening of the injection hole provided in the measuring member. There is provided a fuel injection valve characterized in that: According to the invention of claim 2, the valve body has a needle valve that is received inside the valve body and opens and closes a fuel flow path in a seal portion, and has a plurality of injection holes provided at a tip end of the valve body. In a fuel injection valve including a measuring member that performs measurement of a fuel and determination of an injection direction, an inner wall surface downstream of a seal portion of the valve body is formed so as to be gently continuous with an upstream surface of the measuring member, The seal portion of the needle valve and the bottom surface on the most downstream side cooperate with an inner wall surface downstream of the seal portion of the valve body when the needle valve is opened to introduce fuel into an injection hole provided in the metering member. When the needle valve is opened, the tangential line passing through the point where the spherical shape intersects the bottom surface of the needle and the line of intersection of the metering member are defined by the gauge when the needle valve is opened. A fuel injection valve, characterized in that it is formed so as to be outside the circumscribed circle of the upstream opening of the nozzle holes disposed in member is provided.

[0005] Since the fuel injection valve of the present invention is constructed as described above, when the needle valve is opened, the fuel flows from the gap of the seal portion to the intermediate surface of the downstream needle valve and the inner wall surface of the valve body. The fuel flows obliquely toward the center of the valve through the fuel flow path inclined inwardly and downstream formed between the needle valve and the bottom surface of the needle valve and the surface on the upstream side of the measuring member. The air flows laterally toward the center of the valve through the gap, flows into the injection hole arranged on the way to the center of the valve while separating at the inlet, and is discharged from the outlet.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing the structure of a first embodiment of a fuel injection valve according to the present invention, in which a needle valve 2 is received inside a valve body 1 and a downstream end of the valve body 1 is provided. Has a measuring member 3 attached thereto, and the measuring member 3 has a plurality of injection holes 4.

FIG. 2 is an enlarged view of a portion A in FIG. 1 and shows a state when fuel is injected. In FIG. 2, reference numeral 10 denotes the entire inner wall surface of the valve body 1,
Reference numeral 20 denotes the entire outer wall surface of the needle valve 2, and reference numerals 11 and 21 denote a seal portion of the valve body 1 and a seal portion of the needle valve 2, which abut against each other during a period in which fuel is not injected to cut off the flow of fuel. I do.

The inner wall surface 10 of the valve body 1 uniformly extends from the upstream portion 12 to the downstream portion 13 of the seal portion 11 so as to approach the central axis 100 of the fuel injection valve toward the downstream side. Is formed. In the figure,
Although a portion parallel to the central axis 100 is shown between the valve body 1 and the measuring member 4, this is formed when the valve body 1 is processed.

The outer wall surface 20 of the needle valve 2 has a portion 2 substantially parallel to the central axis 100 on the upstream side of the seal portion 21.
From 2, it reaches the seal portion 21 through the curved surface portion 23, and at the downstream side of the seal portion 21, reaches the bottom surface 25 through the straight portion 24, which is a conical intermediate surface. Straight section 24
And the bottom surface 25 are smoothly connected by a curved surface portion 26. The bottom surface 25 is formed at right angles to the central axis 100.

The upper surface 31 and the lower surface 32 of the measuring member 3 are formed at right angles to the central axis 100. Therefore, the upper surface 31 of the measuring member 3 and the bottom surface 25 of the needle valve 2 are parallel. The injection hole 4 is formed so as to intersect the central axis 100 when the central axis 40 is extended to the upstream side, and the inlet side opening 41 is located inside the outlet side opening 42. Here, a point X at which a line extending from the straight line portion 24 on the downstream side of the seal portion 21 of the outer wall surface 20 of the needle valve 2 to the downstream side intersects the upper surface 31 of the measuring member 3 is indicated by the arrow. It is located outside the outermost edge 43 of the inlet opening 41 of the injection hole 4.

FIG. 3 is a view taken along the line II of FIG. 1, and reference numeral 33 denotes a seal portion 2 on the outer surface 20 of the needle valve 2.
1, a line extending downstream from the straight line portion 24 on the downstream side represents a circle connecting points X that intersect the upper surface 31 of the measuring member 3,
Reference numeral 46 denotes a circumscribed circle connecting the outermost edges 43 of the inlet-side openings 41 of the injection holes 4.

Next, the flow of fuel in the embodiment of the present invention formed as described above will be described. When the needle valve is opened, the fuel passes through a gap between the seal portion 11 of the valve body 1 and the seal portion 21 of the needle valve 2, and then flows through the downstream portion 13 of the valve body 1 and the linear portion 24 on the downstream side of the needle valve 2. The fuel flows through the fuel flow path inclined inward and downstream formed between them as shown by an arrow F1 in FIG. After colliding with the upper surface 31 of the measuring member 3, the measuring member 3
F between the upper surface 31 of the needle valve 2 and the bottom surface 25 of the needle valve 2
2 and flows toward the central axis 100.

Thereafter, the liquid flows into the injection hole 4 through the inlet opening 41 and is discharged from the outlet opening 42 as a liquid column and a liquid film. Therefore, a periodic vortex is generated in the fuel flow immediately after the inlet, and as a result, the fuel passing through the inside of the injection hole 4 changes its width in the direction of arrow C in FIG. The liquid column and liquid film of the fuel are self-excited and the fuel is atomized.

Here, in the present invention, as described above, the fuel first flows downstream of the seal portion as shown by the arrow F1,
Next, the direction is changed as shown by an arrow F2, but since the angle is not large, the fuel does not lose a large amount of kinetic energy due to this change in direction. Therefore, even when the fuel reaches the inlet-side opening 41 of the injection hole 4, the fuel has relatively large kinetic energy, so that the fuel is easily separated from the outermost edge 43 of the inlet-side opening 41. The result is a strong vortex,
The self-excited vibration of the liquid column and liquid film becomes stronger, and the atomization of the fuel is improved.

FIG. 4 is a view showing the structure of a second embodiment of the present invention. A cross section of an intermediate plane connecting the seal portion 21 and the bottom surface 25 of the needle valve 2 is centered on a point 200. The point connected by a circle having the radius R, that is, the point that the intermediate surface has a spherical shape is different from the first embodiment, and the other portions are the same. And this circle is the bottom 25
A tangent line 29 passing through a point 28 intersecting with the upper surface 31 of the measuring member 3
Is located outside the outermost edge 43 of the inlet-side opening 41 of the injection hole 4. The fuel flows as indicated by F1 ′ and F2 ′ in the drawing, and exhibits the same effect as in the first embodiment, but the movement of the flow downstream of the seal portion becomes smoother, so that the fuel moves. Since the energy is less attenuated and the exfoliation from the outermost edge 43 of the inlet-side opening 41 of the injection hole 4 is improved, the atomization of the fuel is further improved. In addition, the dead volume at the time of closing the valve is reduced, and when the needle valve is closed, the amount of the fuel remaining on the downstream side of the seal portion and thereafter being reduced by the suction negative pressure is reduced. The accuracy is improved.

It is to be noted that the bottom surface 25 of the needle valve 2 in each of the above-described embodiments can be variously deformed, for example, to have a spherical shape, a conical shape, or the like.
Alternatively, a concave shape or the like can be considered. 5 and 6
The bottom surface 2 of the needle valve 2 in the second embodiment
5 and 5 show a spherical shape and a conical shape, respectively. In this case, the dead volume is further reduced, and the accuracy is further improved.

[0017]

According to the present invention, the fuel is easily separated at the inlet of the injection hole, the self-excited vibration of the liquid column and the liquid film of the fuel is promoted, and the atomization of the fuel is improved. As a result, the output can be improved or the exhaust gas emission can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG. 1;

FIG. 3 is a view taken along the line II in FIG. 1;

FIG. 4 is an enlarged view showing a structure according to a second embodiment of the present invention.

FIG. 5 is a modified example of the second embodiment.

FIG. 6 is another modification of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Valve body 2 ... Needle valve 3 ... Measuring member 4 ... Injection hole 100 ... Central axis

Continuation of the front page (56) References JP-A-4-50464 (JP, A) JP-A-3-92564 (JP, U) US Patent 5383607 (US, A) (58) Fields investigated (Int. ⁷ , DB name) F02M 61/18 340 F02M 61/18 350

Claims (2)

(57) [Claims] 1. A valve body, a needle valve received inside the valve body for opening and closing a fuel flow path in a seal portion, and a plurality of injection holes disposed at a tip end of the valve body, and having a fuel injection hole. And a fuel injection valve having a measuring member for determining the injection direction, wherein the inner wall surface of the valve body downstream of the seal portion is formed so as to be gently continued to the upstream surface of the measuring member. The seal portion and the bottom surface on the most downstream side are inclined inward and downstream to cooperate with the inner wall surface on the downstream side of the seal portion of the valve body when the needle valve is opened to introduce fuel into an injection hole provided in the metering member. Connected via a conical surface forming a fuel flow path, and when the needle valve is opened, when the conical surface is extended toward the upstream surface of the measuring member, the conical surface extends upstream of the measuring member. A fuel injection valve, wherein an intersection line formed by intersecting with the side surface is formed outside a circumcircle of an upstream opening of an injection hole provided in the measuring member. . 2. A fuel meter having a valve body, a needle valve received inside the valve body and opening and closing a fuel flow path at a seal portion, and a plurality of injection holes disposed at a tip end of the valve body. And a fuel injection valve having a measuring member for determining the injection direction, wherein the inner wall surface of the valve body downstream of the seal portion is formed so as to be gently continued to the upstream surface of the measuring member. The seal portion and the bottom surface on the most downstream side are inclined inward and downstream to cooperate with the inner wall surface on the downstream side of the seal portion of the valve body when the needle valve is opened to introduce fuel into an injection hole provided in the metering member. When the needle valve is opened, a tangential line passing through a point where the spherical shape intersects the needle bottom surface and an intersection line of the measuring member are connected to the measuring member when the needle valve is opened. A fuel injection valve, wherein the fuel injection valve is formed so as to be outside a circumscribed circle of an upstream opening of the arranged injection hole.